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Nanoscale Guiding of Infrared Light with Hyperbolic Volume and Surface Polaritons in van der Waals Material Ribbons
Author(s) -
Dolado Irene,
AlfaroMozaz Francisco Javier,
Li Peining,
Nikulina Elizaveta,
Bylinkin Andrei,
Liu Song,
Edgar James H.,
Casanova Felix,
Hueso Luis E.,
AlonsoGonzález Pablo,
Vélez Saül,
Nikitin Alexey Y.,
Hillenbrand Rainer
Publication year - 2020
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201906530
Subject(s) - polariton , materials science , van der waals force , waveguide , nanoscopic scale , infrared , dispersion (optics) , phonon , surface plasmon polariton , condensed matter physics , optics , photonics , optoelectronics , nanotechnology , plasmon , surface plasmon , physics , quantum mechanics , molecule
Van der Waals (vdW) materials host a variety of polaritons, which make them an emerging material platform for manipulating light at the nanoscale. Due to the layered structure of vdW materials, the polaritons can exhibit a hyperbolic dispersion and propagate as nanoscale‐confined volume modes in thin flakes. On the other hand, surface‐confined modes can be found at the flake edges. Surprisingly, the guiding of these modes in ribbons—representing typical linear waveguide structures—is widely unexplored. Here, a detailed study of hyperbolic phonon polaritons propagating in hexagonal boron nitride ribbons is reported. Employing infrared nanoimaging, a variety of modes are observed. Particularly, the fundamental volume waveguide mode that exhibits a cutoff width is identified, which, interestingly, can be lowered by reducing the waveguide thickness. Further, hybridization of the surface modes and their evolution with varying frequency and waveguide width are observed. Most importantly, it is demonstrated that the symmetrically hybridized surface mode does not exhibit a cutoff width, and thus enables linear waveguiding of the polaritons in arbitrarily narrow ribbons. The experimental data, supported by simulations, establish a solid basis for the understanding of hyperbolic polaritons in linear waveguides, which is of critical importance for their application in future photonic devices.